Improvement in carbon photographs



U ITE STATES PATENT OFFIoE.

CLAUDE LEON LAMBERT, OF PARIS, FRANCE.

IMPROVEMENT IN CARBON PHOTOGRAPHS.

Specification forming part of Letters Patent No. 171,392. dated December21, 1875 application filed I January 4, 1875. i

To all whom it may concern:

Be it known that I, CLAUDE LEON LAM- BERT, of Paris,France,'photographer, have invented Improvements in Producing CarbonPhotographs; and I do hereby declare that the following is a full,clear, and exact description of the same. I

My invention is an improvement in process for producing carbonphotographs or sun-pictures, produced in salts of chromiumor othbothtogether-glass and paper-and subject it to slight pressure for a fewminutes, after which I immerse in warm water, and develop the positiveprint, which, according to the length of exposure, will make either atransparency or a picture seen by reflected light. It is upon thislatter feature (the picture seen by reflected light) that the inventionis based.

The positive picture having been thus developed, I then only have toimmerse it in a bath containing from ten to fifteen per cent. ofgelatine in solution, and to apply the card upon which the photograph isto be mounted,and which is also passed through this bath. The picture isthen allowed to dry completely, and the image is then detached, andremainsas brilliant and glossy as the glass with which it was incontact. This brilliancy is not produced by a layer of gelatine, but bythe image itself,

which is completely insoluble, and will, consequently, bear considerablefriction, and'may even be wetted without affecting its appearance ordurability.

By the above process I obtain an image which is, in fact, unalterable,and which is itselfpreserved by an almost unattackable body, (insolublebichromated gelatine,) t. 6., the picture itself, and which is obtainedin its true aspectthat is to say, non-reversed. Thus, in practice, itwill not be necessary to have two poses to produce apendant-that istosay,

two portraits ofpersons face to face. i

The gradual strengthening which I apply to the salts of chromiumconsists ofla solution of eleven ounces(three hundred grams) of water,one drop of liquid ammonia, and fifteen grains (1 gram) of sugar, inaddition to which is added, according to the desired intensity of thenegative, a few drops of saturated solution of permanganate of potassa.The negative obtained from a transparent positive is then placed in abath containing the above solution, and, if it is desired to obtainstill greater intensity, some more saturated permanganate of potassa isadded. The negative, thus strengthened,

will produce prints of thesame quality as wouldthe original negative. Inthis manner, also, transparent positives may be intensified, in order toimpart greater brilliancy to the negativ'eto be obtained therefrom.

To obtain prints in salts of chromium on ordinary albnmenized paper,with borders in a scale of difi'erent tints, which contrast with that ofthe picture, I take ordinary albumenized, paper of any quality,andexpose it to light after sensitizing; then place it in the press, takingcare to preserve a blank forithe picture, with a black or yellow mask,and in this manner obtain an impression from a negative of anyornamental border, with a blank space reserved for thepicture. Ithenprecipitate it with hyposulphite, and fix as in ordinary cases, and, ifnecessary, apply it to my oval or square photographs. I thus obtaintints which harmonize perfectly-one for the picture, and the other forthe border.

I'claim v 1. A compound consisting of eleven ounces of water, fifteengrains of sugar, one drop of liquid ammonia, and a few drops ofpermanganate of potassa, to form a bath in which a negative obtainedfrom atransparent posi-,

tive may be immersed, and thus intensified.

2. The process 'of obtaining double-tinted prints in salts of chromiumand on ordinary albumenized paper, by placing the sensitized paper in apress, the blank for the picture he I I ing covered with a black oryellow mask, and

the whole being then precipitated by hyposulphite, as described.

CLAUDE Leon LAMBERT.

Witnesses:

GHARLES Dnsnos, ROBT. M. HooPEn.

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